Approximately 38.4 million Americans have been diagnosed with asthma by a health professional during their lifetime. This chronic inflammatory disease places a significant burden on both the health care system and individual patients, with annual expenditures for health and lost productivity due to asthma estimated at over $20 billion. In spite of high morbidity and costs, most asthmatic patients have mild-to-moderate disease and about 5-8% of asthmatic patients fall into the category of “chronic severe asthma” (CSA). Asthmatic patients have significant reduction in quality of life as a result of their asthma, have frequent hospital admissions and emergency visits, and account for a much larger percentage of overall health care costs. Clinically, asthma is characterized by a component of irreversible airflow obstruction and peripheral airways disease, ongoing mediator release and a reduced association with atopy. There is currently no way to predict whether an individual patient with asthma will be stable over time, or exhibit declining lung function that leads to development of CSA.
Current asthma treatment and diagnosis are predominantly clinically based, or use pulmonary function testing, which is expensive, can only occur in specialized pulmonary function testing laboratories, and is inconvenient. Exhaled breath NO is another recent test used in asthma, but it lacks specificity and sensitivity for diagnosis and monitoring of asthma treatment/severity. Further, it is not readily collected and sent to laboratory for testing, like most other diagnostic tests. Rather, it takes specialized instrumentation to be located on-site for testing. Simple reliable and objective quantitative measures of blood or urine based tests for the diagnosis of asthma, and for predicting risk of exacerbation, need for therapeutic titration, or monitoring of response to therapeutic interventions, are needed.